Bell’s palsy is a neurologic disorder that affects the seventh cranial (facial) nerve, producing unilateral facial weakness or paralysis. Onset is rapid. Although it affects all age-groups, it’s most common in persons younger than age 60. In 80% to 90% of patients, it subsides spontaneously, with complete recovery in 1 to 8 weeks; however, recovery may be delayed in older adults. If recovery is partial, contractures may develop on the paralyzed side of the face. Bell’s palsy may recur on the same or opposite side of the face.
The seventh cranial nerve is responsible for motor innervation of the facial muscles. With Bell’s palsy, the nerve is blocked by an inflammatory reaction around the nerve (usually at the internal auditory meatus). This is commonly associated with infections (most likely herpes simplex) and can result from hemorrhage, tumor, meningitis, or local trauma.